A drive assembly comprises a housing, a drive member moveable for setting a dose and for delivering the dose. A piston rod adapted to be driven by the drive member in the distal direction during movement of the drive member in the distal direction for dose delivery and a restriction member for restricting proximal movement of the piston rod during proximal movement of the drive member by mechanical interaction of the restriction member with a stop feature. The restriction member and stop feature arranged for the piston rod to be moved proximally a first distance during a first movement of the drive member before the restriction member and stop feature interact mechanically. The first distance the piston rod moves proximally during the first movement of the drive member is different than a subsequent distance the piston rod moves during a subsequent proximal movement of the drive member.
